Mark Kornblau, the head of PR for NBC News and MSNBC, also weighed in on Twitter, saying, “Never imagined a day when I would think to myself, ‘it is beneath my dignity to respond to the President of the United States.'”

In a statement, an MSNBC spokesperson added, “It’s a sad day for America when the president spends his time bullying, lying and spewing petty personal attacks instead of doing his job.”

Never imagined a day when I would think to myself, "it is beneath my dignity to respond to the President of the United States."